Steer axle assembly

ABSTRACT

A steer axle assembly in accordance with the present invention includes an axle beam defining a first boss with a first bore. The assembly further includes a knuckle body that defines a second boss. The second boss is in the form of a unitary sleeve from which a tie rod arm and steering arm extend. The second boss includes a second bore. The assembly further includes a set of bearings disposed in one of the first and second bores. In one embodiment of the invention, the bearings are disposed in the axle beam bore. In another embodiment of the invention, the bearings are disposed in the bore defined by the knuckle body. The assembly finally includes a kingpin. The kingpin is rotatably received within the bore having the bearings and is rigidly coupled within the bore that does not include the bearings. The kingpin may be tightened to its required specification via the use of a washer and nut on one end of the kingpin.

This application is a continuation of, and claims priority to, U.S.application Ser. No. 09/633,383 filed on Aug. 7, 2000, now U.S. Pat. No.6,499,752 the entire disclosure of which is incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Technical Field

This invention relates to steer axle assemblies and more particularly toa two boss steer axle assembly incorporating bearings to allow rotationof the kingpin.

2. Discussion of the Background Art

In a conventional steer axle assembly, a steering knuckle provides aspindle or bearing support for a wheel hub, bearings and wheel assembly.The steering knuckle is coupled to the steer axle using a kingpin.Typically, the steering knuckle has a forked yoke that defines first andsecond bosses with aligned bores. The yoke surrounds one end of thesteer axle which defines a third boss having another bore aligned withthe bores of the knuckle yoke. The kingpin extends through one of theknuckle bores, through the axle bore, and through the remaining knucklebore to couple the knuckle and steer axle together.

In these conventional steer axle assemblies, the kingpin is fixedlycoupled to the axle boss such that the kingpin does not rotate inrelation to the axle boss. The knuckle pivots about the kingpin on avertical steering axis. Typically, bushings are disposed within thealigned bores of the knuckle to allow the knuckle to rotate relative tothe kingpin.

Conventional steer axle assemblies suffer from several disadvantages.First, conventional steer axle assemblies allow a relatively largeamount of axial and radial movement of the kingpin. As a result of thisaxial and radial movement, the kingpin joints are subject to greaterwear, thereby creating greater clearances and permitting the kingpin toshift and oscillate within the knuckle bores and reducing the usefullives of the assembly components. In order to limit axial and radialmovement of the kingpin, shimming and precision machining of the steeraxle assembly members are often required. Second, the use of a knucklehaving a yoke (i.e., two bosses): (i) requires a relatively large numberof seals; (ii) increases tooling, manufacturing, and assembly costs dueto the relatively complex design; (iii) minimizes the ability to adjustthe drop of the steer axle from the spindle; (iv) increases the size andweight of the assembly; and (v) prevents a predictable and relativelynarrow tolerance range of bearing pre-load/endplay because assembly andvehicle loading causes deflection of bearings disposed within thebosses. Third, the use of bushings in conventional steer axle assembliesresults in relatively large tolerances and often requires broaching orreaming of the bushings.

There is thus a need for a steer axle assembly that will minimize oreliminate one or more of the above-mentioned deficiencies.

SUMMARY OF THE INVENTION

The present invention provides a steer axle assembly.

A steer axle assembly in accordance with the present invention includesan axle beam defining a first boss with a first bore. The assemblyfurther includes a knuckle having a body that defines only a second bossas compared to the conventional knuckle that defines second and thirdbosses. The second boss is in the form of a unitary sleeve from which atie rod arm and steering arm extend. The second boss includes a secondbore. The assembly further includes a set of bearings disposed in one ofthe first and second bores. In one embodiment of the invention, thebearings are disposed in the axle beam bore. In another embodiment ofthe invention, the bearings are disposed in the bore defined by theknuckle body. The assembly finally includes a kingpin. The kingpin isrotatably received within the bore having the bearings and is rigidlycoupled within the bore that does not include the bearings. The kingpinmay be tightened to its required specification via the use of a washerand nut on one end of the kingpin.

A steer axle assembly in accordance with the present inventionrepresents a significant improvement as compared to conventional steeraxle assemblies. First, axial and radial movement of the kingpin isdiminished because such movement can be easily and consistentlymonitored and adjusted—without shimming or precision machining. Second,the two boss system of the inventive assembly provides for a simplifiedknuckle design and manufacture. The use of two bosses as opposed tothree also provides: (i) improved life of the joint because of thedecrease in the number of seals and necessary adjustments; (ii)decreased tooling, manufacturing and assembly costs; (iii) the abilityto easily change the kingpin length and/or spacer size to change thedrop in the axle beam thereby reducing the need for multiple gooseneckbeam forgings with different gooseneck drops from the spindle to thebeam spring pad or center section; (iv) a reduction in the overall sizeand weight of the assembly with the ability to accommodate a variety ofbrake styles and positions; (v) the ability to obtain a predictable andnarrow tolerance range or bearing pre-load/endplay; and (vi) the abilityto use structural steel of various cross-sections in addition to forgedbeams. Finally, the use of bearings, as opposed to bushings, within theboss bores provides: (i) the ability to obtain finer tolerances; (ii) areduction in the variation in joint movement; and (iii) lowermaintenance and manufacturing costs.

These and other features and objects of this invention will becomeapparent to one skilled in the art from the following detaileddescription and the accompanying drawings illustrating features of thisinvention by way of example.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional and elevational view of a steer axle assembly inaccordance with a first embodiment of the present invention.

FIG. 2 is a sectional and elevational view of a steer axle assembly inaccordance with a second embodiment of the present invention.

FIG. 3 is a sectional and elevational view of a steer axle assembly inaccordance with the first embodiment of the present inventionillustrating a different configuration for the kingpin.

FIGS. 4-7 are sectional and elevational views of a steer axle assemblyin accordance with the first embodiment of the present inventionillustrating the use of various bearing configurations.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings wherein like reference numerals are usedto identify identical components in the various views, FIG. 1illustrates a steer axle assembly 10 in accordance with a firstembodiment of the present invention. Assembly 10 is configured for usein large trucks, but may find application in a wide variety of vehicles.In accordance with the present invention, assembly 10 includes an axlebeam 12, a knuckle 14, a kingpin 16, and a set of bearings 18. Assembly10 may also include a spacer 20, a nut 22, and a washer 24.

Axle beam 12 is provided to support a vehicle (not shown) on wheels (notshown) disposed proximate either end of beam 12. Beam 12 may be made befrom steel and may be forged or fabricated. Each end (only one of whichis shown in FIG. 1) of beam 12 defines a first boss 26. In theillustrated embodiment, boss 26 forms the lower boss (i.e., the bossthat is closer to ground) of the two-boss assembly 10. This constructionfacilities the use of straight beams made of structural steel of variouscross-sections in addition to conventional forged I-beams (generallyhaving a gooseneck) because the drop of the axle beam may be variedthrough the size of kingpin 16 and/or spacer 20 rather than the axlebeam as described hereinbelow. Boss 26 includes a bore 28 extendinggenerally vertically and substantially perpendicular to the longitudinalaxis of beam 12. Bore 28 is configured to receive kingpin 16.

Knuckle 14 is provided for mounting of a wheel (not shown) of thevehicle and for connecting axle beam 12 and the steering components ofthe vehicle. Knuckle 14 may be made from steel and may be forged orfabricated. Knuckle may include a body 30, steering and tie-rod arms 32,34, a spindle 36, and a brake mounting plate 38.

Body 30 provides structural support for the other components of knuckle14 and defines a second boss 40 for receipt of kingpin 16. Boss 40 is inthe form of a unitary sleeve from which steering and tie-rod arms 32, 34extend and includes a bore 42 configured to receive kingpin 16. Theangle of axle bore 28 and knuckle bore 42 are such to position kingpin16 generally vertically, preferably at some angle inboard from avertical position to assist steering.

Arms 32, 34 are provided to couple knuckle 14 to the steering mechanismof the vehicle and to a support rod (not shown) extending generallyparallel to beam 12. Arms 32, 34 are conventional in the art and—asillustrated in FIG. 1—may be integral with body 30. Alternatively, arms32, 34 may be bolted onto body 30 or connected via a tapered fist orother conventional arrangement. In the case wherein arms 32, 34 are madeintegral with body 30, arms 32, 34 may initially extend in a directionparallel to spindle 36 as knuckle 14 is formed and then be urged intotheir respective final positions.

Spindle 36 is provided to mount a wheel (not shown) of a vehicle onwheel bearings (not shown). Spindle is conventional in the art and maybe formed integral with body 30.

Braking mounting plate 38 is provided to support a brake (not shown) fora wheel. Plate 38 may be integral with body 30 of knuckle 14 or may beattached to knuckle 14 in a variety of conventional ways. The inventiveassembly 10 facilitates the use of a wide variety of brakes. Forexample, plate 38 may comprise a conventional round flange.Alternatively plate 38 may be formed so as to receive various air discor hydraulic brakes.

Kingpin 16 is provided to couple knuckle 14 to beam 12. Kingpin 16 maybe made from steel or other conventional metals or metal alloys. Kingpin16 has a first portion rotatably supported by bearings 18 within bore 42of knuckle body 30 and a second portion fixedly coupled within bore 28of beam 12. Referring to FIG. 2, in a steer axle assembly 10′ inaccordance with a second embodiment of the present invention, kingpin 16has a first portion rotatably supported by bearings 18 within bore 28 ofbeam 12 and a second portion fixedly coupled within bore 42 of knucklebody 30. Kingpin 16 may be fixedly coupled within bore 28 of beam 12 (orbore 42 of knuckle body 30 in the case of assembly 10′) in aconventional manner through the use of one or more drawkeys.

Referring again to FIG. 1, kingpin 16 has a longitudinal body 44disposed about an axis 46 with a first axial end defining an end flange48 and a second axial end defining a partially threaded shank 50. Flange48 extends radially outwardly from body 44 and is disposed against beam12 adjacent the end 52 of bore 28 closest to ground. Shank 50 extendsfrom body 44 in the direction of axis 46 and has a diameter that is lessthan the diameter of body 44. Shank 50 extends outwardly from end 54 ofbore 42 of knuckle body 30. Referring to FIG. 3, in an alternateembodiment of a steer axle assembly 10″ in accordance with the presentinvention, flange 48 may be disposed against bearings 18 adjacent end 54of bore 42 and shank 50 may extend outwardly from end 52 of bore 28 ofbeam 12.

Bearings 18 are provided to allow relative rotation between kingpin 16and either knuckle 14 (in assembly 10) or beam 12 (in assembly 10′). Inthe case of assembly 10′—where bearings 18 are disposed in the lowerboss 26 (i.e., the boss that is closer to ground)—bearings 18 maycomprise conventional wheel bearings because the short distance betweenbearings 18 and ground as compared to conventional steer axle assembliesreduces the load required during braking of the vehicle. Bearings 18 maytake on a variety of forms. Referring to FIG. 1, bearings 18 maycomprise a unitized or cartridge bearings sold under the trademark“UNIPAC” by Timken Corp. Bearings 18 include first and second bearingcones 56, 58 with cones 56, 58 adjacent to one another. Cones 56, 58form inner bearing races and provide a bearing surface for kingpin 16.Bearings 18 further include a unitary bearing cup 60 disposed radiallyoutwardly of both cone 56 and cone 58 and forming a pair of outerbearing races. Cup 60 is sized so as to be received within bore 42 ofknuckle body 30 (or, bore 28 of beam 12 in the case of assembly 10′ inFIG. 2). Alternatively, cup 60 may be made integral with knuckle body30.

Referring to FIG. 4, another alternative set of bearings 18′ for usewithin the inventive steer axle assemblies is illustrated. Bearing set18′ may comprise a wide-spread version of the unitized or cartridgebearings illustrated in FIG. 1. Bearing set 18′ includes first andsecond bearing cones 62, 64 separated by a spacer 66. Cones 62, 64 forminner bearing races and provide a bearing surface for kingpin 16.Bearings 18′ further include a unitary bearing cup 68 disposed radiallyoutwardly of both cone 62 and cone 64 and spacer 66 and forming a pairof outer bearing races. Cup 68 is sized so as to be received within bore42 of knuckle body 30 (or, bore 28 of beam 12 in the case of assembly10′ in FIG. 2). Alternatively, cup 68 may be made integral with knucklebody 30.

Referring to FIG. 5, an alternative set of bearings 18″ for use withinthe inventive steer axle assemblies is illustrated. Bearing set 18″ maycomprise the manually adjusted bearings having model number 2T-S andmanufactured by Timken Corp. Bearings 18″ include first and secondbearing cones 70, 72 that are separated from one another along axis 46.Cones 70, 72 form inner bearing races and provide a bearing surface forkingpin 16. Bearings 18″ further include bearing cups 74, 76 disposedradially outwardly of cones 70, 72, respectively and forming a pair ofcorresponding outer bearing races. Cups 74, 76 are sized so as to bereceived within bore 42 of knuckle body 30 (or, bore 28 of beam 12 inthe case of assembly 10′ in FIG. 2).

Referring to FIG. 6, yet another alternative set of bearings 18′″ foruse within the inventive steer axle assemblies is illustrated. Bearingset 18′″ may comprise the pre-set bearings having model number 2T-S andmanufactured by Timken Corp. Bearing set 18′″ includes first and secondbearing cones 78, 80 that are separated from one another along axis 46.A spacer 82 is disposed between cones 78, 80. Cones 78, 80 form innerbearing races and provide a bearing surface for kingpin 16. Bearings18′″ further include bearing cups 84, 86 disposed radially outwardly ofcones 78, 80, respectively and forming a pair of corresponding outerbearing races. Cups 84, 86 are sized so as to be received within bore 42of knuckle body 30 (or, bore 28 of beam 12 in the case of assembly 10′in FIG. 2).

Referring to FIG. 7, yet another alternative set of bearings 18″″ foruse within the inventive steer axle assemblies is illustrated. Bearingset 18″″ may comprise the bearings sold under the trademark “WHEELPAC”by Timken Corp. Bearing set 18″″ includes first and second bearing cones88, 90 with cones 88, 90 adjacent to one another. Cones 88, 90 forminner bearing races and provide a bearing surface for kingpin 16.Bearing set 18″″ further includes bearing cups 92, 94 disposed radiallyoutwardly of cones 88, 90, respectively and forming a pair ofcorresponding outer bearing races. Cups 92, 94 are sized so as to bereceived within bore 42 of knuckle body 30 (or, bore 28 of beam 12 inthe case of assembly 10′ in FIG. 2). Although FIGS. 4-7 illustratevarious bearing sets disposed within bore 42 of knuckle body 30, itshould be readily understood by those of skill in the art that theillustrated bearings could alternatively be disposed in bore 28 of beam12 as illustrated in FIG. 2.

Referring again to FIG. 1, spacer 20 is provided to maintain apredetermined distance between beam 12 and knuckle 14. Spacer 20 isconventional in the art and may be made from conventional metals orother solid materials. Spacer 20 is annular and the inner diameter issized to receive kingpin 16. One side of spacer 20 is configured toengage bearings 18. An opposite side of spacer 20 is configured toengage beam 12 (or knuckle body 30 in the case of assembly 10′ in FIG.2). The axial length of spacer 20 may be varied in order to vary thedrop of beam 12.

Nut 22 and washer 24 are provided to enable the application of aninitial bearing pre-load to the kingpin joint. Nut 22 and washer 24 maybe made from conventional metals and are sized to receive shank 50 ofkingpin 16. Nut 22 and washer 24 may be combined into a one-pieceflanged nut. Washer 24 is disposed about an unthreaded portion of shank50. Turning nut 22 produces a predefined bearing pre-load acting throughwasher 24, bearings 18 (which may comprise one or more bearing conesand/or spacers depending upon the bearing set used), spacer 20, beam 12(or knuckle body 30 in the case of assembly 10′ in FIG. 2) and endflange 48. As set forth hereinabove, in each of the bearings 18, 18′,18″, 18′″, 18″″ disclosed herein, both bearing rows are disposed withina single boss 40 of knuckle 14 (or boss 26 of beam 12 in the case ofassembly 10′). As a result, a predictable and narrow tolerance range ofbearing pre-load/end play can be obtained by tightening nut 22. In aconventional three-boss steer axle assembly, the bearing rows aredisposed in separate bosses on the knuckle body and deflection occursduring assembly and under vehicle static and dynamic load therebyprecluding the ability to obtain and retain narrow tolerances. Nut 22and washer 24 may be disposed within an enclosure cap (not shown)coupled to knuckle 14.

As described and illustrated hereinabove, a steer axle assembly inaccordance with the present invention represents a significantimprovement as compared to conventional steer axle assemblies. First,the arrangement allows easy application of an initial bearing pre-loadby tightening nut 22. As a result, axial and radial movement of kingpin16 is reduced without shimming or precision machining. Second, thesingle boss knuckle 14: (i) improves the life of the kingpin jointbecause only a single set of seals are needed; (ii) decreases tooling,manufacturing and assembly costs because of the simple design of theknuckle; (iii) enables a relatively easy adjustment of the axle beamdrop through variation in the length of the kingpin 16 and/or spacer 20thereby reducing or eliminating the need to have multiple beam forgingswith different gooseneck drops from the spindle to the spring pad orcenter section of beam 12; (iv) reduces the overall size and weight ofthe assembly; (v) accommodates a variety of brake styles and positions;(vi) provides the ability to obtain a predictable and narrow tolerancerange of bearing pre-load/endplay; and (vii) facilitates the use ofstructural steel beams of various cross-sections in addition to forgedbeams. Finally, the use of bearings 18, as opposed to bushings, withinthe boss bores 28, 42 provides: (i) the ability to obtain finertolerances; (ii) a reduction in the variation in joint movement; and(iii) lower maintenance and manufacturing costs.

It is to be understood that the above description is merely exemplaryrather than limiting in nature, the invention being limited only by theappended claims. Various modifications and changes may be made theretoby one of ordinary skill in the art which embody the principles of theinvention and fall within the spirit and scope thereof.

I claim:
 1. A steer axle assembly, comprising: a steer axle beamdefining a first boss, said first boss having a first bore; a knucklehaving a body, said body disposed on only one side of said axle beam anddefining a second boss having a second bore; a set of bearings disposedwithin one of said first and second bores; and, a kingpin having a firstportion supported by said bearings in said one bore and a second portionfixedly coupled within another of said first and second bores.
 2. Theassembly of claim 1 wherein said set of bearings includes first andsecond bearing cones and a spacer disposed between said first and secondbearing cones.
 3. The assembly of claim 1 wherein said set of bearingsincludes first and second bearing cones and a unitary bearing cupdisposed radially outwardly of said first and second bearing cones. 4.The assembly of claim 1 wherein said set of bearings includes first andsecond bearing cones adjacent one another.
 5. A steer axle assembly,comprising: a steer axle beam defining a first boss, said first bosshaving a first bore; a knuckle having a body, said body disposed on onlyone side of said axle beam and defining a second boss having a secondbore; a set of bearings disposed within said first bore; and, a kingpinhaving a first portion supported by said bearings in said first bore anda second portion fixedly coupled within said second bore.
 6. Theassembly of claim 5 wherein said bearings include first and secondbearing cones and a spacer disposed between said first and secondbearing cones.
 7. The assembly of claim 5 wherein said set of bearingsincludes first and second bearing cones and a unitary bearing cupdisposed radially outwardly of said first and second bearing cones. 8.The assembly of claim S wherein said set of bearings includes first andsecond bearing cones adjacent one another.
 9. The assembly of claim 5,further comprising a spacer disposed between said bearings and saidknuckle.
 10. The assembly of claim 5, further comprising: a nut; and, awasher wherein said kingpin includes a first end defining a flange and asecond end defining a shank and said nut and said washer are disposedabout said shank.
 11. The assembly of claim 10 wherein said flange isdisposed against said knuckle and said washer is disposed against saidbearings.
 12. The assembly of claim 10 wherein said flange is disposedagainst bearings and said washer is disposed against said knuckle.
 13. Asteer axle assembly, comprising: a steer axle beam defining a firstboss, said first boss having a first bore; a knuckle having a body, saidbody disposed on only one side of said axle beam and defining a secondboss having a second bore; a set of bearings disposed within said secondbore; and, a kingpin having a first portion supported by said bearingsin said second bore and a second portion fixedly coupled within saidfirst bore.
 14. The assembly of claim 13 wherein said bearings includefirst and second bearing cones and a spacer disposed between said firstand second bearing cones.
 15. The assembly of claim 13 wherein said setof bearings includes first and second bearing cones and a unitarybearing cup disposed radially outwardly of said first and second bearingcones.
 16. The assembly of claim 13 wherein said set of bearingsincludes first and second bearing cones adjacent one another.
 17. Theassembly of claim 13, further comprising a spacer disposed between saidbearings and said axle beam.
 18. The assembly of claim 13, furthercomprising: a nut; and, a washer wherein said kingpin includes a firstend defining a flange and a second end defining a shank and said nut andsaid washer are disposed about said shank.
 19. The assembly of claim 18wherein said flange is disposed against said axle beam and said washeris disposed against said bearings.
 20. The assembly of claim 18 whereinsaid flange is disposed against bearings and said washer is disposedagainst said axle beam.